A base station device in a mobile communication system allocates, based on the communication quality of each radio channel defined by frequencies, time, and the like, part of the radio channels as a communication channel to be used for communication to/from a mobile station device. Then, the base station device notifies the mobile station device of the allocated communication channel. As a standard for such a mobile communication system, for example, Non Patent Literature 1 discloses the next-generation PHS standard.